1. Field of the Invention.
This invention relates to an improved low-profile outrigger for use with a dorsal wrist splint and, more particularly, to an improved apparatus and method of adjusting the tension in the rigging thereof.
2. Prior Art.
Dynamic hand splints are used to provide dynamic forces to the digits of a hand. These splints are particularly useful for extension of the proximal interphalangeal joints. Dynamic hand splints are often used after implant resection arthroplasty of the metacarpophalangeal joints of a hand These type of splints are used for a number of purposes including: promotion of tissue synthesis, promotion of tendon gliding, assistance of the lymphatic pump, prevention and correction of deformity, increasing the range of motion, assistance to neurologic function, prevention of softer tissue adhesion, and protection for healing tissues. The amount of force applied varies. However, it is generally believed that the maximum force that should be used in dynamic splinting is approximately 300 grams. In prior art dynamic splints, the dynamic force is generated by rubber bands and colorcoded springs, which generate a specific force.
U.S. Pat. No. 4,765,320 by Lindemann et al. entitled "Dynamic Low Profile Splint" discloses a dynamic splint which has an outrigger structure mounted on a forearm piece. A key element disclosed by this patent is an elongated laterally adjustable "rigging guide" which is part of a pulley system mounted on the outrigger structure. The rigging guide operates as a pulley for changing the direction and the amount of force applied by a rigging to a finger sling. A fastening clamp for the rigging guide is rotated to vary the tension of the rigging. Tension is generated with an "elastic band." The rigging guide is an extra arm which extends distally from the outrigger structure over a finger and is adjustably mounted to vary the force on the rigging.
U.S. Pat. No. 4,602,620 entitled "Dynamic Outrigger Extension for Dorsal Wrist Splints," by Ralph Marx discloses an outrigger structure having a number of wheels mounted thereupon for guiding a rigging line attached to a finger sling. The outrigger structure has a rigging which includes a rubber band as a dynamic force member. The end of the rigging is attached to a fixed point on a forearm. Improvements to the outrigger structure disclosed in the Marx '620 patent include substitution of fixed-length springs for the rubber bands. To obtain a particular spring force, one particular type of spring is used. To obtain a different force, another type of spring having the same length but with a different characteristic is used because the attachment point for the rigging on the forearm is fixed. To identify the different types of springs, the springs are color-coded.